As electronic typewriters become more sophisticated and provide ever increasing function, the products are following the lead of personal computers in that the functions or features may be added to the basic typewriter by the attachment of an auxiliary device which contains the necessary code to control the typewriter in the desired manner.
The approaches that have been followed in adding function to typewriters includes the use of dedicated circuit boards which are contained within an enclosure which is then attached to the typewriter both electronically and physically. This approach is cumbersome and limits the operator to a few optional functions.
Computers and more recently typewriters have begun using cartridges for the addition of function and memory capacity. The cartridges are connected to the electronics of the typewriter or computer by engaging a connector and a land pattern of a circuit board. To insure adequate contact between the connector and the lands, the connector exerts a significant force on the land when the connection is made. This force also serves to impede the removal of the connector. The natural tendency of the operator is to insert and remove the cartridge by rocking the cartridge relative to the circuit board of the machine. This is undesirable, particularly with cartridges which require that the electronic circuitry be electrically grounded prior to making the functional connections, since the ground protection is typically designed for a straight push insertion, and extraction.
Additionally, it is desirable from a design standpoint, to have the cartridge contained within the machine housing as much as possible. This not only makes the appearance of the machine more pleasing, but also minimizes the possibility of causing a machine malfunction through undesired impact of the cartridge.
The desired low profile or minimal exposure of the cartridge requires that only a minimum of the cartridge be exposed to the grip of the operator and thus hinders the extraction of the cartridge due to the small grip area and the relatively high engaging force exerted by the connector on the circuit board lands.
U.S. Pat. No. 1,900,782 to C. M. May discloses a light plug which has a bellcrank lever movable by a person's thumb to pull the plug from the electrical wall socket. This device, while well suited for the environment in which it is used, exerts a force well off the center of the plug blades and actually tend to induce rocking or tilting of the plug, which in the present environment is very undesirable, as described above.